The present invention relates to gates in general, and in particular to a rotary feeder for dosing flowable (bulk) material.
A rotary feeder includes a housing formed with a top inlet and a bottom outlet which are spaced apart from one another by an internal chamber. Accommodated in the chamber is a rotor supported on a shaft for rotation about a pivot axis. The shaft is rotatably journalled in spaced-apart side covers and carries a plurality of radially extending vanes between spaced-apart end disks. Shaft seals are provided for sealing the internal chamber of the housing from the ambient environment. When the shaft is driven, batches of flowable material entering through the inlet are advanced in the cells between neighboring vanes and discharged through the outlet.
A rotary feeder of this type is disclosed in German pat. No. 37 42 521 C1 and describes the provision of a complicated seal arrangement in order for this conventional rotary feeder to operate at high pressure differentials between the inlet and the outlet. The bearings for the rotor shaft are located at the outside in the side covers and are protected against penetration of, in particular, dusty particles in a direction toward the internal chamber by a plurality of seal shafts fitted on the shaft. This type of rotary feeder displays comparably wide dimensions so that the rotor shaft is either caused to sag at high pressure differentials, thereby enlarging the normal operational play on one side and diminishing the normal operational play on the other side, or is of such massive design in order to give it a necessary rigidity. Clearly, a massive design of the rotor shaft complicates manufacture and thus is cost-intensive, while a sagging of the rotor shaft inevitably leads to an increased friction and thus heating in the peripheral area of the rotor as well as in the area of the shaft and shaft seals.